/**
 * 
 */
package com.ly.mpayment.core.util;

import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;


/**
 *
 */
public class MD5 {

	private static final char HEX_DIGITS[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
		'A', 'B', 'C', 'D', 'E', 'F' };

	 public static String toHexString(byte[] b) {
	        StringBuilder sb = new StringBuilder(b.length * 2);
	        for (int i = 0; i < b.length; i++) {
	            sb.append(HEX_DIGITS[(b[i] & 0xf0) >>> 4]);
	            sb.append(HEX_DIGITS[b[i] & 0x0f]);
	        }
	        return sb.toString();
	    }

	 public final static String MD5Convert(String s) {
	        char hexDigits[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};       
	        try {
	            byte[] btInput = s.getBytes();
	            // 获得MD5摘要算法的 MessageDigest 对象
	            MessageDigest mdInst = MessageDigest.getInstance("MD5");
	            // 使用指定的字节更新摘要
	            mdInst.update(btInput);
	            // 获得密文
	            byte[] md = mdInst.digest();
	            // 把密文转换成十六进制的字符串形式
	            int j = md.length;
	            char str[] = new char[j * 2];
	            int k = 0;
	            for (int i = 0; i < j; i++) {
	                byte byte0 = md[i];
	                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
	                str[k++] = hexDigits[byte0 & 0xf];
	            }
	            return new String(str).toLowerCase();
	        } catch (Exception e) {
	            e.printStackTrace();
	            return null;
	        }
	    }
	    public static String md5sum(String filename) {
	        InputStream fis;
	        byte[] buffer = new byte[1024];
	        int numRead = 0;
	        MessageDigest md5;
	        try{
	            fis = new FileInputStream(filename);
	            md5 = MessageDigest.getInstance("MD5");
	            while((numRead=fis.read(buffer)) > 0) {
	                md5.update(buffer,0,numRead);
	            }
	            fis.close();
	            return toHexString(md5.digest());  
	        } catch (Exception e) {
	            System.out.println("error");
	            return null;
	        }
	    }
}
